Method and apparatus for rebuilding valve guides

ABSTRACT

This disclosure relates to a method and system for rebuilding valve guides for internal combustion engines wherein the old worn guides are first reamed and then have slitted tubular members forced into the reamed guides. The tubular member inserts can then be reamed to size. The operation can also include knurling and broaching of the tubular members after insertion of the tubular member into the reamed valve guide. The tubular member has an outer diameter greater than the inner diameter of the reamed guide so that a press fit between the tubular member and the guide results.

llite atnt [191 Kammeraa et a1.

Filed:

METHOD AND APPARATUS FOR REBUTUDTNG VALVE GUIDES lnventors: Donald J.Kammeraad, 4563,

Venessa Ave.; James A. Kammeraad, Rt. 2, both of Holland, Mich. 49423Dec. 30, 1971 Appl. No.: 214,261

Related US. Application Data abandoned.

Continuation of Ser/ No. 847,927, Aug. 6, 1969,

29/451, 525, 156.4 WL; 123/188 P, 188 VA, 188 CC, 188 SA, 90.67; 308/5V, 237 R References Cited UNITED STATES PATENTS Ford 123/9067 Smith29/156.4 WL Towler 123/188 GC Taylor 308/5 V Surtces 29/156.4 WL

[ Aug. 13, 1974 2,414,931 1/1947 2,674,782 4/1954 Surtees 29/156.4 WL

FOREIGN PATENTS OR APPLICATIONS 582,438 9/1958 ltaly 123/188 GC 869,3845/1961 Great Britain 123/188 GC Primary Examiner-Richard J. HerbstAssistant ExaminerE. M. Combs Attorney, Agent, or Firm--Price, Heneveld,Huizenga & Cooper [5 7] STRACT This disclosure relates to a method andsystem for rebuilding valve guides for internal combustion engineswherein the old worn guides are first reamed and then have slittedtubular members forced into the reamed guides. The tubular memberinserts can then be reamed to size. The operation can also includeknurling and broaching of the tubular members after insertion of thetubular member into the reamed valve guide. The tubular member has anouter diameter greater than the inner diameter of the reamed guide sothat a press fit between the tubular member and the guide results.

4 Claims, 8 Drawing Figures Colwell et a1 29/156.4 WL

METHOD AND APPARATUS FOR REBUILDING VALVE GUIDES This application is acontinuation of co-pending application Ser. No. 847,927 entitled METHODAND APPARATUS FOR REBUILDING VALVE GUIDES filed Aug. 6, 1969, nowabandoned.

This invention relates to rebuilding valve guides. In one of itsaspects, it relates to rebuilding valve guides wherein the old guidesare first reamed and slittedtubular members are then forced into thereamed guides.

In another of its aspects, the invention relates to a system forrebuilding valve guides in which a reaming means is provided to ream outthe old valve guide, a tubular member having a longitudinal slit isprovided, and means are provided for forcing the tubular member into areamed valve guide to provide a press fit between the reamed valve guideand the tubular member.

Valve guides for internal combustion engines become worn throughextended use. It is necessary for the valve guide to have closetolerances between the valve stem and the valve guides in order for theengine to operate efficiently.

Tools have been devised for effectively reducing the diameter ofa holesuch as valve guides. In U.S. Pat. No. 3,097,426, for example, there isdisclosed a tool for reducing the effective diameter of a hole byforming flat crested threads within the hole. This tool cannot always beused for rebuilding valve guides, however, because in many instances thevalve guides are so badly worn that there is insufficient metal to formthe desired inner diameter of the guide.

Other systems have been developed for rebuilding valve guides. One suchsystem drills and reams out valve guides and then inserts a tubular castiron cylinder into the reamed out hole. The excess portion of thecylinder is then trimmed off. The thickness of the cast iron cylinder isnecessarily about seventy-five to onehundred thousands of an inch.Substantial amounts of metal must be removed from the valve guidenecessitating the use of precision drilling equipment. Numerous jigs,dies, guides and leveling devices, and special power units are requiredwith the system. As a result a large capital investment is required touse the same. Further, the wearability of the new valve guide is aboutthe same as that of the original valve guide.

Another system first drills an anchor hole in a valve guide. Then aself-piloting tap is threaded into the valve guide. A phosphor bronzespiral bushing is then threaded into the threaded valve guide with aspecial tool. Excess material is removed from the ends of the bushingand a broach is forced through the guide to set the bushing in place.The valve guide is then reamed to size. The tapping of the valve guideis a complicated operation and the insertion of the spiral bushing isdifficult.

l have now discovered still another system and method for rebuildingvalve guides wherein the use of a slotted tubular member as a valveguide permits a simple system of tools to be used to quickly, easily andeffectively rebuild the guides.

By various aspects of this invention one or more of the following, orother, objects can be obtained.

lt is an object of this invention to provide a system and method forrebuilding valve guides wherein a few simple tools are employed.

It is another object of this invention to provide. a sys-.

tem and method for quickly and easily rebuilding valve It is yet anotherobject of this invention to provide-a method and system for rebuildingvalve guides wherein the rebuilt guides have maximum heat transferproperties to minimize wear of the rebuilt guides.

It is another object of this invention to provide an improved rebuiltvalve guide having improved wear characteristics and closer tolerancesfor more efficient en gine operation. 1 Other aspects, objects, and theseveral advantages of this invention are apparent to one skilled in theart from a study of this disclosure, the drawings, and the appendedclaims.

According to the invention there is provided a method for rebuildingvalve guides comprising the steps of reaming said valve guides so as toexpand the diameter thereof, forcing a tubular longitudinal insert intothe reamed valve guides to provide a new surface for the guide. Theinserts have an outer diameter, greater than the inner diameter of thereamed hole and have a longitudinal slit extending the length thereof sothat the tubular member conforms in a press fit to the inner diameter ofthe reamed valve guide.

Further according to theinvention, the metal of the insert is flowed tojoin the slit thereby preventing the oil from flowing through the slitwithin the valve guides. Preferably the tubular insert is made fromphosphor bronze for greater wearability of the rebuilt guides.

Further according to the invention, the tubular memher is formed byprogressively forming cut blanks from sheet stock into a tubular shape.The longitudinal slit in the tubular member can be formed by offsetportions such that the slit is nonlinear, or can be formed byinterengaging finger portions which abut each other at thecircumferential edges thereof.

Still further according to the invention there is provided a system forrebuilding valve guides comprising a means forreaming the valve guide, atubular member having a slit extending longitudinally from one end tothe other and adapted to fit coextensively within said valve guide. Theouter diameter of the tubular member is slightly greater than the outerdiameter of the reams ing means. Means are also provided for forcing thetubular member into a reamed valve guide, thereby making a press fitbetween the tubular member and the reamed valve guide.

Still further according to the invention a valve guide for an internalcombustion engine has a valve guide formed from a cylindrical hole inthecylinder head, a cylindrical thin wall tubular member is firmlysecured in the cylindrical hole, the tubular member having alongitudinal seam from one end to the other. The wall thickness of thetubular member is preferably in the range of ten to twenty-tivethousands of an inch and the tubular member is preferably made from aphosphor bronze.

The invention will now be described with reference to the accompanyingdrawings in which:

FIG. 1 is a partial side elevational view in section of a typical valveguide and valve stem in operating position;

FIG. 2 is a view of the valve guide similar to FIG. 1 illustrating afirst step of the method of the invention;

FIG. 3 is a perspective view of a tubular insert used in practicing theinvention;

FIG. 4 is a side elevational view of the valve guide like FIG. 2, butshowing a second step of the process;

FIG. 5 is a side elevational view of the valve guide illustrated inFIGS. 2 and 4 showing a further step in the process;

FIG. 6 is a view similar to FIG. 5 showing the rebuilt valve guide aftera knurling operation;

FIG. 7 is a perspective view of a modified tubular member; and

FIG. 8 is a perspective view of still another modified tubular member.

Referring now to the drawings, and to FIG. 1 in particular, an overheadvalve engine head 10 has machined therein a valve guide 11 with anexposed shoulder portion indicated generally by the reference numeral 12through which the valve stem 13 is passed during assembly. Ordinarily,the exposed shoulder 12 will be integrally cast with the remainder ofthe head and thereafter machined to proper dimensions. A valve spring 14encircles exposed shoulder portion 12 of the valve guide assembly andthe valve is conventionally retained with respect thereto by a pair ofvalve keepers 18. While not shown, of course, the valve stem 13 extendsdownwardly and terminates in a valve portion having a suitable seatmachined into the lower surface of the head 10. The valve spring 14retains the valve in closed position with respect to the seat exceptwhen forced downwardly by a rocker arm (not shown) or the like in properoperational sequence. An oil seal prevents oil from flowing between thevalve stem 16 and the valve guide 11 and into the combustion chamber ofthe engine.

The seal 20 is retained in compressive abutment by means of theretaining boot assembly 22 which has a tubular base member 24 adapted totelescopically engage the outer diameter of the valve guide 12 throughindent 26. The seal structure is more fully described and claimed inUnited States Patent Application Ser. No. 675,586, filed Oct. 16, I967.

Referring now to FIG. 2, there is shown a first step in the valverebuilding guide method. The valve stem 16 and its associated componentsare removed from the shoulder portion 12. A reamer tool 30 having athreaded section 32 with a tapered leading portion 34 and a sizingportion 36 is forced through the valve guide. The reamer tool 30 is aself-piloting tool so that the axis of the reamed valve guide is thesame as the original axis of the guide. The reamer tool 30 has a reamersection comprised of longitudinal flutes 38 which cuts away and therebyexpands the diameter of the valve guide.

Referring now to FIG. 3 a tubular member 40 is stamped from a blank ofphosphor bronze and pregressively formed into a tubular shape, leaving alongitudinal slit 42.

Referring now to FIG. 4, the tubular insert 40 is forced into the reamedvalve guide 11' by means of an adaptor 44 having a tapered innerdiameter 46. The outer diameter of the tubular member 40 is greater thanthe reamed valve guide 11 so that the tubular insert 40 must be radiallycompressed in order to force the same into the reamed valve guide 11.The adaptor 44 is annular shaped. At the upper portion, the innerdiameter of the adaptor is greater than the outer diameter of thetubular insert 40. At the lower portion, the inner diameter of theadaptor 44 is equal to or less than the inner diameter of the reamedvalve guide 11.

A forcing tool 48 is positioned in the upper portion of the tubularinsert 40 and is struck at the top portion thereof to force the tubularinsert through the adaptor 44 and into the reamed valve guide 11. Theforcing tool 48 may have a lower circumferential rim as illustrated inthe drawing or may be flat.

The tubular insert v40 can be cut from a blank so as to be exactly thelength of the valve guide. Alternately standard size blanks can be usedwith an excess length trimmed off when the tubular members have beeninserted into the valve guides. Thus, when the tubular insert 40 iscompletely within the valve guide as illustrated in FIG. 5, with the topportion of the tubular insert 40 even with the top surface of theshoulder portion 12, the tubular insert 40 will be coextensive with thereamed valve guide 11. Further, the blanks are so dimensioned that theslit 42 is closed forming a longitudinal seam as the tubular insert isforced into the reamed valve guide. The slit 42 is thereby held closedby the circumferential pressure from the valve guide 11' on insert 40.The wall thickness of the tubular inserts can be in the range of ten totwenty-five thousands of an inch and preferably in the range of fifteento twenty thousands of an inch. Preferably the tubular inserts are madefrom phosphor bronze for maximum wearability At this point, the valveguide is ready for use. However, additional steps can also be performedto improve still further the rebuilt valve guide structure.

For example, as illustrated in FIG. 6, the inner surface of the tubularinsert 40 can be knurled as at 50 to flow the metal of the tubularinsert. This knurling process flows the metal of the tubular insert 40so as to seal off the passage through slit 42. By this step, the oilwithin the engine is prevented from seeping through the valve guide 11.In addition, the knurling operation more firmly seats the insert 40within the reamed valve guide. Many tools are available for thisknurling operation. One such tool is disclosed in U.S. Pat. No.3,038,253.

After the knurling operation, the valve guide can then be reamed againto a predetermined size diameter if necessary. The rebuilt valve guidewill then be as good as or better than the original valve guide of theengine.

In a modified procedure, the rebuilt valve guide illustrated in FIG. 5can be broached with a common broaching tool in order to flow the metalin the same manner as was done with the knurling tool.

The modified tubular insert 52 illustrated in FIG. 7 hascircumferentially offset slits 54 and 56 which are contiguous and form alongitudinal slit in the tubular insert. This modified tubular insert 52can be formed in the same manner as the tubular insert 40, ie.,,

stamped from tubular stock and progressively formed in dies into atubular shape.

Another modified tubular insert 60 is illustrated in FIG. 8. Thismodified insert has interlocking finger 62 and 64 which form in thetubular insert longitudinal slit 66 having a tortuous path. Theinterlocking fingers 62 and 64 abut at the circumferential edges thereofso that when the tubular member 60 is inserted within the valve guide,oil will not be able to flow through the longitudinal slit 66 from oneend to another. However, oil pockets can be left at the open slitportion 66 to provide oil retaining means for lubricating the valve stemwithin the valve guide.

This modified tubular insert 60 is formed in the same manner as thetubular insert 40, i.e., by stamping the same out of blanks of I metal,preferably phosphor bronze, and then progressively forming the stampedblanks into a tubular shape as illustrated.

The use of the longitudinal slits facilitate the insertion of thetubular member into the reamed valve guide so that a press fit ismaintained between the tubular insert and the reamed valve guide.Further, the forma tion of the tubular inserts are simple andinexpensive with the stamping and forming operations. By the nature ofthe interlocking relationship of the tubular inserts 52 and 60, nomaterial is wasted in the stamping operation.

The stamping operation is very precise and precision parts can be formedthereby. The tubular inserts formed by such process can be preciselyformed from thin gage phosphor bronze or other similar material. Thethinner the material is, the better the operation of the valve guides.The interface between the insert and the engine block retards the heatflow away from the valve guides during operation. It has been found thatas the wall thickness of the inserts decreases, the retarding effect ofthe interface decreases. Therefore, it is desirable to use a thin amaterial as possible without mitigating the wearability of the valveguide. By the use of the blanks, the wall thickness can be reduced toabout ten thousands 0t an inch.

Further, with the use of the sheet stock to form the tubular inserts,the final inner diameter of the valve guide cam be controlled with fargreater accuracy than guide, as with prior art systems, the alignment ofthe reaming tools is more critical and must be controlled with morecomplicated equipment and more complicated procedures.

Reasonable variation and modification are possible within the scope ofthe foregoing disclosure, the drawings, and appended claims withoutdeparting from the spirit of the invention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. In an internal combustion engine having a plurality of valve guideswithin which a series of valves are reciprocally mounted, at least someof said valve guides including a sleeve-like member positioned within anelongated cylindrical bore in said engine, the improvement in saidmember comprising said member being thin-walled and formed from phosphorbronze, said member, when installed, being substantially coextensivewith said bore such that said member terminates substantially flush withthe axial extremities of said bore and having the form of a cylinderhaving a substantially straight longitudinal exterior surface whichcontacts said bore and a substantially straight longitudinal interiorsurface which contacts the stem of the valves, said member including anoffset longitudinal slit formed therealong and extending the lengththereof, said longitudinal slit comprising at least two interengagingfinger portions which abut each other at the circumferential edges ofsaid member; said member, in relaxed condition prior to insertion insaid bore, being expanded in cross section larger than the diameter ofsaid bore with the sidewall portions bounding said longitudinal slitbeing separated from one another, said member, in confined conditionafter axial insertion into said bore, being radially compressed by andin tight abutment with the inner diameter of said bore so that saidmember is generally circular in cross section with the sidewall portionsbounding said slit being in abutment with one another, said sidewallportions being retained in such abutment and said member being retainedwithin said bore by the radial compression of said bore.

2. The structure as set forth in claim 1 wherein the wall thickness ofsaid member is in the range of ten to twenty-five thousandths of aninch.

3. The structure as set forth in claim 1 wherein said member is formedby progressively forming cut blanks of sheet stock into a tubular shape.

4. The structure as set forth in claim 1 wherein said longitudinal slitis formed of a plurality of interengaging finger portions which abuteach other at the circumferential edges of said member.

1. In an internal combustion engine having a plurality of valve guideswithin which a series of valves are reciprocally mounted, at least someof said valve guides including a sleeve-like member positioned within anelongated cylindrical bore in said engine, the improvement in saidmember comprising said member being thinwalled and formed from phosphorbronze, said member, when installed, being substantially coextensivewith said bore such that said member terminates substantially flush withthe axial extremities of said bore and having the form of a cylinderhaving a substantially straight longitudinal exterior surface whichcontacts said bore and a substantially straight longitudinal interiorsurface which contacts the stem of the valves, said member including anoffset longitudinal slit formed therealong and extending the lengththereof, said longitudinal slit comprising at least two interengagingfinger portions which abut each other at the circumferential edges ofsaid member; said member, in relaxed condition prior to insertion insaid bore, being expanded in cross section larger than the diameter ofsaid bore with the sidewall portions bounding said longitudinal slitbeing separated from one another, said member, in confined conditionafter axial insertion into said bore, being radially compressed by andin tight abutment with the inner diameter of said bore so that saidmember is generally circular in cross section with the sidewall portionsbounding said slit being in abutment with one another, said sidewallportions being retained in such abutment and said member being retainedwithin said bore by the radial compression of said bore.
 2. Thestructure as set forth in claim 1 wherein the wall thickness of saidmember is in the range of ten to twenty-five thousandths of an inch. 3.The structure as set forth in claim 1 wherein said member is formed byprogressively forming cut blanks of sheet stock into a tubular Shape. 4.The structure as set forth in claim 1 wherein said longitudinal slit isformed of a plurality of interengaging finger portions which abut eachother at the circumferential edges of said member.